Just a quick tip: if you’re seeing the error message “Audio synchronization failure – Could not synchronize one or more clips in the current selection because a match could not be found” when trying to create a multicam clip synched via audio tracks on large files (inhale) – make sure you’ve waited long enough for the audio to conform.
This threw me off today after importing two hour-long clips that I needed to use for a multicam clip. When I checked each clip, Cam A was fine, but Cam B had no audio. Since I was using a rented camera for Cam B, I assumed something might have gone wrong with the on-board mic (Cam A had the real mics), before remembering to check if the audio had been conformed yet.
Since audio takes so long to conform in Premiere Pro, I had already googled the problem and read three different dead-ends before I opened the clip again and discovered the audio magically appeared.
An easy mistake to make, so I just thought I’d post this for anyone else impatiently googling that error and not finding the answer. Check the bottom right of your screen to see if it’s still conforming!